Predictors of disease course in patients with probable Alzheimer's disease.

The presence of extrapyramidal signs or psychosis may indicate greater disability in patients with probable Alzheimer's disease. We evaluated the ability of these signs, noted at a patient's first visit, to predict one of two specific clinical endpoints: (1) a preselected score on the modified Mini-Mental State examination (cognitive endpoint), and (2) a preselected score on the Blessed Dementia Rating Scale (functional endpoint). Sixty-five patients were followed either until they reached the endpoints or to the end of the study period. Survivorship curves were drawn to predict the distribution of time to onset of an endpoint in patients with and without the clinical signs. Time to reach the cognitive endpoint was shorter for patients with extrapyramidal signs or psychosis compared with those without these signs and symptoms. These clinical signs did not predict the functional endpoint. We conclude that extrapyramidal signs and psychosis may be useful predictors of intellectual decline in Alzheimer's disease.